There are very few functional differences between SKS and Planet Bike's top of the line fenders, for the "chomo-plastic" varieties. Some might argue that various metal fenders (Berthoud, Velo Orange, etc) are better, but that is more a matter of personal taste or opinion than functionality. You are talking about pretty basic, simple technology here. I wouldn't lose any sleep worrying about which one is "best" but would base my decisions on what looks best and serves your particular needs. I prefer plastic fenders over metal because they are lighter weight and don't dent, but I'm sure than metal fans have their reasons.